From: "Paul E. McKenney" <paulmck@kernel.org>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Alan Stern <stern@rowland.harvard.edu>,
Marco Elver <elver@google.com>,
Eric Dumazet <edumazet@google.com>,
Eric Dumazet <eric.dumazet@gmail.com>,
syzbot <syzbot+3ef049d50587836c0606@syzkaller.appspotmail.com>,
linux-fsdevel <linux-fsdevel@vger.kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
syzkaller-bugs <syzkaller-bugs@googlegroups.com>,
Al Viro <viro@zeniv.linux.org.uk>,
Andrea Parri <parri.andrea@gmail.com>,
LKMM Maintainers -- Akira Yokosawa <akiyks@gmail.com>
Subject: Re: KCSAN: data-race in __alloc_file / __alloc_file
Date: Sun, 10 Nov 2019 13:31:38 -0800 [thread overview]
Message-ID: <20191110213138.GH2865@paulmck-ThinkPad-P72> (raw)
In-Reply-To: <CAHk-=wjm40mcf7tk9DZQXd=dftZw_VpmE837c7pTZ1_cR+t4Mw@mail.gmail.com>
On Sun, Nov 10, 2019 at 01:10:39PM -0800, Linus Torvalds wrote:
> On Sun, Nov 10, 2019 at 12:44 PM Paul E. McKenney <paulmck@kernel.org> wrote:
> >
> > But will "one size fits all" be practical and useful?
>
> Oh, I do agree that if KCSAN has some mode where it says "I'll ignore
> repeated writes with the same value" (or whatever), it could/should
> likely be behind some flag.
>
> I don't think it should be a subsystem flag, though. More of a "I'm
> willing to actually analyze and ignore false positives" flag. Because
> I don't think it's so much about the code, as it is about the person
> who looks at the results.
>
> For example, we're already getting push-back from people on some of
> the KCSAN-inspired patches. If we have people sending patches to add
> READ_ONCE/WRITE_ONCE to random places to shut up KCSAN reports, I
> don't think that's good.
>
> But if we have people who _work_ on memory ordering issues etc, and
> want to see a strict mode, knowing there are false positives and able
> to handle them, that's a completely different thing..
>
> No?
Understood on the pushback! And I especially agree that it is bad to
automatically add *_ONCE() just to shut up KCSAN. For one thing, doing
that inconveniences people later on who might want to take a closer look.
As long as I can get the full-up reports for RCU. And as long as the
others who want the full-up reports can also get them. ;-)
And agreed, if the results are adjusted based on who is processing them,
that should be good.
Thanx, Paul
next prev parent reply other threads:[~2019-11-10 21:31 UTC|newest]
Thread overview: 67+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <CAHk-=wjB61GNmqpX0BLA5tpL4tsjWV7akaTc2Roth7uGgax+mw@mail.gmail.com>
2019-11-10 16:09 ` KCSAN: data-race in __alloc_file / __alloc_file Alan Stern
2019-11-10 19:10 ` Marco Elver
2019-11-11 15:51 ` Alan Stern
2019-11-11 16:51 ` Linus Torvalds
2019-11-11 17:52 ` Eric Dumazet
2019-11-11 18:04 ` Linus Torvalds
2019-11-11 18:31 ` Eric Dumazet
2019-11-11 18:44 ` Eric Dumazet
2019-11-11 19:00 ` Linus Torvalds
2019-11-11 19:13 ` Eric Dumazet
2019-11-11 20:43 ` Linus Torvalds
2019-11-11 20:46 ` Linus Torvalds
2019-11-11 21:53 ` Eric Dumazet
2019-11-11 23:51 ` Linus Torvalds
2019-11-12 16:50 ` Kirill Smelkov
2019-11-12 17:23 ` Linus Torvalds
2019-11-12 17:36 ` Linus Torvalds
2019-11-17 18:56 ` Kirill Smelkov
2019-11-17 19:20 ` Linus Torvalds
2019-11-11 18:50 ` Linus Torvalds
2019-11-11 18:59 ` Marco Elver
2019-11-11 18:59 ` Eric Dumazet
2019-11-10 19:12 ` Linus Torvalds
2019-11-10 19:20 ` Linus Torvalds
2019-11-10 20:44 ` Paul E. McKenney
2019-11-10 21:10 ` Linus Torvalds
2019-11-10 21:31 ` Paul E. McKenney [this message]
2019-11-11 14:17 ` Marco Elver
2019-11-11 14:31 ` Paul E. McKenney
2019-11-11 15:10 ` Marco Elver
2019-11-13 0:25 ` Paul E. McKenney
2019-11-12 19:14 ` Alan Stern
2019-11-12 19:47 ` Linus Torvalds
2019-11-12 20:29 ` Alan Stern
2019-11-12 20:58 ` Linus Torvalds
2019-11-12 21:13 ` Linus Torvalds
2019-11-12 22:05 ` Marco Elver
2019-11-12 21:48 ` Alan Stern
2019-11-12 22:07 ` Eric Dumazet
2019-11-12 22:44 ` Alexei Starovoitov
2019-11-12 23:17 ` Eric Dumazet
2019-11-12 23:40 ` Linus Torvalds
2019-11-13 15:00 ` Marco Elver
2019-11-13 16:57 ` Linus Torvalds
2019-11-13 21:33 ` Marco Elver
2019-11-13 21:50 ` Alan Stern
2019-11-13 22:48 ` Marco Elver
2019-11-08 13:16 syzbot
2019-11-08 13:28 ` Eric Dumazet
2019-11-08 17:01 ` Linus Torvalds
2019-11-08 17:22 ` Eric Dumazet
2019-11-08 17:38 ` Linus Torvalds
2019-11-08 17:53 ` Eric Dumazet
2019-11-08 17:55 ` Eric Dumazet
2019-11-08 18:02 ` Eric Dumazet
2019-11-08 18:12 ` Linus Torvalds
2019-11-08 20:30 ` Linus Torvalds
2019-11-08 20:53 ` Eric Dumazet
2019-11-08 21:36 ` Linus Torvalds
2019-11-08 18:05 ` Linus Torvalds
2019-11-08 18:15 ` Marco Elver
2019-11-08 18:40 ` Linus Torvalds
2019-11-08 19:48 ` Marco Elver
2019-11-08 20:26 ` Linus Torvalds
2019-11-08 21:57 ` Alan Stern
2019-11-08 22:06 ` Linus Torvalds
2019-11-09 23:08 ` Alan Stern
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